A fuel injection valve is described in German Patent Application No. DE 195 00 706 A1.
The device for metering liquids and gases, described in German Patent Application No. DE 195 00 706 A1, in particular in fuel injection valves in internal combustion engines, has a hydraulic displacement amplifier for converting the actuator travel of a piezoelectric actuator into an increased stroke of a valve needle. To spatially integrate the displacement amplifier in the valve housing to give a small overall volume, the lifting piston of the displacement amplifier is provided with an end section that has a reduced diameter and projects into a recess in the working piston of the displacement amplifier. A disk spring lying in the amplifier chamber bordered by the pistons presses the working piston against the actuator, and a helical compression spring arranged in the recess concentrically to the end section presses the lifting piston against the valve needle.
Influences from temperature changes, wear, and manufacturing tolerances on the actuator displacement of the actuator are compensated for in that in each case a hollow-cylindrical restrictor gap, via which the amplifier chamber is linked to a liquid-filled low-pressure space, is provided on the guide surfaces of the pistons, between the pistons and between the pistons and the inside wall of the valve housing. The volume defined by the amplifier chamber, the restrictor gaps, and the low-pressure space is sealed.
In the case of the lifting device known from German Patent Application No. DE 195 00 706 A1, above all the costly construction and the overall length of the valve are disadvantageous. The relatively large volume and relatively large cross-sectional area of the actuator also do not allow for a particularly compact design. In addition, the large displacement volumes result in a high cavitation tendency in the restrictor gaps.
The fuel injection valve according to the present invention has the advantage that the lifting device is flexibly configured, and that the temperature is easily compensated in addition to translating and reversing lift.
The seals configured as corrugated tubes are flexible, so that linear deformations are compensated for.
In addition, the flexibility of the seals improves the dynamic performance of the fuel injection valve, since the flexible corrugated tubes prevent the valve-closure member from chattering on the valve-seat surface and, as such, largely prevent the fuel injection valve from opening again. The result is increased accuracy in the metering times and metering amounts.
As a result of the partial accommodation of the valve needle in the central recess of the actuator, the tube-shaped actuator allows for a particularly compact and light design of the fuel injection valve, a tube-shaped valve needle sealed with respect to a nozzle body being at the same time used for supplying fuel to the sealing seat.